Cross-country skiing (sport)
The sport of cross-country skiing encompasses a variety of formats for cross-country skiing races over courses of varying lengths according to rules sanctioned by the International Ski Federation and by various national organizations, such as the U. S. Ski and Snowboard Association and Cross Country Ski Canada. International competitions include the FIS Nordic World Ski Championships, the FIS Cross-Country World Cup, at the Winter Olympic Games; such races occur over homologated, groomed courses designed to support classic and freestyle events, where the skiers may employ skate skiing. It encompasses cross-country ski marathon events, sanctioned by the Worldloppet Ski Federation, cross-country ski orienteering events, sanctioned by the International Orienteering Federation. Related forms of competition are biathlon, where competitors race on cross-country skis and stop to shoot at targets with rifles, paralympic cross-country skiing that allows athletes with disabilities to compete at cross-country skiing with adaptive equipment.
Norwegian army units were skiing for sport in the 18th century. Starting in the latter part of the 20th century, technique evolved from the striding in-track classic technique to include skate-skiing, which occurs on courses that have been groomed with wide lanes for those using the technique. At the same time, equipment evolved from skis and poles that were made of wood and other natural materials to comprising such man-made materials as fiberglass, carbon fiber, polyethylene plastics. Athletes train to achieve endurance, speed and flexibility at different levels of intensity. Offseason training occurs on dry land, sometimes on roller skis; the organization of cross-country ski competitions aims to make those events accessible both to spectators and television audiences. As with other sports that require endurance and speed, some athletes have chosen to use banned performance-enhancing drugs. In 1767 Danish-Norwegian general, Carl Schack Rantzau, codified four classes of military skiing contests and established prizes for each: Shooting at prescribed targets at 40–50 paces while skiing downhill at "top speed".
"Hurling" themselves while racing downhill among trees "without falling or breaking skis". Downhill racing on large slopes without "riding or resting on their stick" or falling. "Long racing" with full military kit and a gun on the shoulder over ca. 2.5 km of "flat ground" within 15 minutes. An early record of a public ski competition was for an 1843 event in Tromsø; the announcement called the event a "wagering race on skis". A distinct alpine technique emerged around 1900 from how skiing was practiced up until when Mathias Zdarsky advocated the "Lilienfelder Ski Method" as an alternative to the Norwegian technique. In Norwegian, langrenn refers to "competitive skiing where the goal is to complete a specific distance in pre-set tracks in the shortest possible time". Alpine skiing competitions existed in Norway during the 18th and 19th centuries, but were discontinued when the main ski festival in Oslo focused on long races and ski jumping; the alpine disciplines reemerged in Central Europe around 1920.
Ski touring competitions are long-distance cross-country competitions open to the public, competition is within age categories. In the 1800s racers used a single, wooden pole, longer and stronger than modern poles, could be used for braking downhill, as well. In Norway, racing with two poles met with resistance, starting in the 1880s, when some race rules forbade them; as the use of pairs of pole became the norm, materials favored lightness and strength, starting with bamboo, which gave way to fiberglass, used at the 1968 Winter Olympics, used at the 1972 Winter Olympics, carbon fiber, introduced in 1975. Skate skiing was introduced to competition in the 20th Century. At the first German ski championship, held at the Feldberg in the Black Forest in 1900, the Norwegian Bjarne Nilssen won the 23 km cross-country race and was observed using a skating motion while skiing—a technique unknown to the spectators. Johan Grøttumsbråten used the skating technique at the 1931 World Championship in Oberhof, one of the earliest recorded use of skating in competitive cross-country skiing.
This technique was used in ski orienteering in the 1960s on roads and other firm surfaces. Finnish skier Pauli Siitonen developed a variant of the style for marathon or other endurance events in the 1970s by leaving one ski in the track while skating outwards to the side with the other ski. American skier Bill Koch further developed the marathon skate technique in the late 1970s. Skate skiing became widespread during the 1980s after Koch's success with it in the 1982 Cross-country Skiing Championships drew more attention to the technique. Norwegian skier, Ove Aunli, started using the technique in 1984, when he found it to be much faster than classic style. Skating is most effective on wide, groomed trails, using fiberglass skis that glide well. Athletes adopted skating to both sides by the time of the 1985 world championship and it was formally adopted by the FIS in 1986—despite initial opposition from Norway, the Soviet Union and Finland—while preserving events using only classic technique.
Snow refers to forms of ice crystals that precipitate from the atmosphere and undergo changes on the Earth's surface. It pertains to frozen crystalline water throughout its life cycle, starting when, under suitable conditions, the ice crystals form in the atmosphere, increase to millimeter size and accumulate on surfaces metamorphose in place, melt, slide or sublimate away. Snowstorms develop by feeding on sources of atmospheric moisture and cold air. Snowflakes nucleate around particles in the atmosphere by attracting supercooled water droplets, which freeze in hexagonal-shaped crystals. Snowflakes take on a variety of shapes, basic among these are platelets, needles and rime; as snow accumulates into a snowpack, it may blow into drifts. Over time, accumulated snow metamorphoses, by sintering and freeze-thaw. Where the climate is cold enough for year-to-year accumulation, a glacier may form. Otherwise, snow melts seasonally, causing runoff into streams and rivers and recharging groundwater. Major snow-prone areas include the polar regions, the upper half of the Northern Hemisphere and mountainous regions worldwide with sufficient moisture and cold temperatures.
In the Southern Hemisphere, snow is confined to mountainous areas, apart from Antarctica. Snow affects such human activities as transportation: creating the need for keeping roadways and windows clear. Snow affects ecosystems, as well, by providing an insulating layer during winter under which plants and animals are able to survive the cold. Snow develops in clouds; the physics of snow crystal development in clouds results from a complex set of variables that include moisture content and temperatures. The resulting shapes of the falling and fallen crystals can be classified into a number of basic shapes and combinations, thereof; some plate-like and stellar-shaped snowflakes can form under clear sky with a cold temperature inversion present. Snow clouds occur in the context of larger weather systems, the most important of, the low pressure area, which incorporate warm and cold fronts as part of their circulation. Two additional and locally productive sources of snow are lake-effect storms and elevation effects in mountains.
Mid-latitude cyclones are low pressure areas which are capable of producing anything from cloudiness and mild snow storms to heavy blizzards. During a hemisphere's fall and spring, the atmosphere over continents can be cold enough through the depth of the troposphere to cause snowfall. In the Northern Hemisphere, the northern side of the low pressure area produces the most snow. For the southern mid-latitudes, the side of a cyclone that produces the most snow is the southern side. A cold front, the leading edge of a cooler mass of air, can produce frontal snowsqualls—an intense frontal convective line, when temperature is near freezing at the surface; the strong convection that develops has enough moisture to produce whiteout conditions at places which line passes over as the wind causes intense blowing snow. This type of snowsquall lasts less than 30 minutes at any point along its path but the motion of the line can cover large distances. Frontal squalls may form a short distance ahead of the surface cold front or behind the cold front where there may be a deepening low pressure system or a series of trough lines which act similar to a traditional cold frontal passage.
In situations where squalls develop post-frontally it is not unusual to have two or three linear squall bands pass in rapid succession only separated by 25 miles with each passing the same point in 30 minutes apart. In cases where there is a large amount of vertical growth and mixing the squall may develop embedded cumulonimbus clouds resulting in lightning and thunder, dubbed thundersnow. A warm front can produce snow for a period, as warm, moist air overrides below-freezing air and creates precipitation at the boundary. Snow transitions to rain in the warm sector behind the front. Lake-effect snow is produced during cooler atmospheric conditions when a cold air mass moves across long expanses of warmer lake water, warming the lower layer of air which picks up water vapor from the lake, rises up through the colder air above, freezes and is deposited on the leeward shores; the same effect occurs over bodies of salt water, when it is termed ocean-effect or bay-effect snow. The effect is enhanced when the moving air mass is uplifted by the orographic influence of higher elevations on the downwind shores.
This uplifting can produce narrow but intense bands of precipitation, which deposit at a rate of many inches of snow each hour resulting in a large amount of total snowfall. The areas affected by lake-effect snow are called snowbelts; these include areas east of the Great Lakes, the west coasts of northern Japan, the Kamchatka Peninsula in Russia, areas near the Great Salt Lake, Black Sea, Caspian Sea, Baltic Sea, parts of the northern Atlantic Ocean. Orographic or relief snowfall is caused when masses of air pushed by wind are forced up the side of elevated land formations, such as large mountains; the lifting of air up the side of a mountain or range results in adiabatic cooling, condensation and precipitation. Moisture is removed by orographic lift, leaving drier, warmer air on the leeward side; the resulting enhanced productivity of snow fall and the decrease in temperature with elevation means that snow depth
Nordic skiing encompasses the various types of skiing in which the toe of the ski boot is fixed to the binding in a manner that allows the heel to rise off the ski, unlike Alpine skiing, where the boot is attached to the ski from toe to heel. Recreational disciplines include Telemark skiing. Olympic events are cross-country skiing, ski jumping and nordic combined—competition in which athletes both cross-country ski and ski jump; the FIS Nordic World Ski Championships host these sports, plus Telemark skiing, at the championship level in the winter of every odd numbered year. Biathlon combines cross-country skiing and rifle shooting, but is not included as a Nordic discipline under FIS rules. Instead, it is under the jurisdiction of the International Biathlon Union; the biomechanics of competitive cross-country skiing and ski jumping have been the subject of serious study. Cross-country skiing requires strength and endurance and ski jumping requires aerodynamic efficiency, both of which requirements translate into specific skills to be optimized in training and competition
Modern competitive archery
Modern competitive archery involves shooting arrows at a target for accuracy from a set distance or distances. This is called target archery. A form popular in Europe and America is field archery, shot at targets set at various distances in a wooded setting. There are several other lesser-known and historical forms, as well as archery novelty games; the World Archery Federation, composed of 156 national federations and other archery associations, is the governing body recognized by the International Olympic Committee. Various other large organizations exist with different rules. Modern competitive target archery is governed by the World Archery Federation, abbreviated as WA. Olympic rules are derived from WA rules. Target archery competitions outdoors. Indoor distances are 18 m. Outdoor distances range from 25 m to 90 m. Competition is divided into ends of 3 or 6 arrows. After each end, the competitors retrieve their arrows. Archers have a set time limit in. 3 arrows are shot in 2 minutes, 6 in 4 minutes.
Targets are marked with 10 evenly spaced concentric rings, which have score values from 1 through 10 assigned to them. In addition, there is an inner 10 ring, sometimes called the X ring; this becomes the 10 ring at indoor compound competitions. Outdoors, it serves. Archers score each end by summing the scores for their arrows. Line breakers, an arrow just touching a scoring boundary line, will be awarded the higher score. In the past, most targets in competitive archery use some kind of stalks of grain or grass and may be constructed of marsh grass woven into a rope wrapped around into a target. However, in modern times, most archery targets are made of synthetic foam, or woven plastic bags stuffed with cloth. Different rounds and distances use; these range from 40 cm to 122 cm. Field archery involves shooting at targets of varying distance in rough terrain. Three common types of rounds are the field and animal. A round consists of 28 targets in two units of 14. Field rounds are at'even' distances up to 80 yards, using targets with a black bullseye, a white center ring, black outer ring.
Hunter rounds use'uneven' distances up to 70 yards, although scoring is identical to a field round, the target has an all-black face with a white bullseye. Children and youth positions for these two rounds are closer, no more than 30 and 50 yards, respectively. Animal rounds use life-size 2D animal targets with'uneven' distances reminiscent of the hunter round; the rules and scoring are significantly different. The archer shoot their first arrow. If it hits, they do not have to shoot again. If it misses, they advance to station two and shoots a second arrow to station three for a third if needed. Scoring areas are nonvital with points awarded depending on which arrow scored first. Again and youth shoot from reduced range. One goal of field archery is to improve the technique required for bowhunting in a more realistic outdoor setting, but without introducing the complication and guesswork of unknown distances; as with golf, fatigue can be an issue as the athlete walks the distance between targets across sometimes rough terrain.
IFAA Field and International rounds are used in European Professional Archery competition. The following are listed on the WA website; these competitions are not as popular as the two listed above, but they are competed internationally. 3D archery is a subset of field archery focusing on shooting at life-size models of game and is popular with hunters. It is most common to see unmarked distances in 3D archery, as the goal is to recreate a hunting environment for competition. Though the goal is hunting practice, hunting broadheads are not used, as they would tear up the foam targets too much. Normal target or field tips, of the same weight as the intended broadhead, are used instead. In the past 10 years 3D archery has taken new light with a competitive edge. There is a whole new group of competitions. Competitions are held in many U. S. states with the totals from each state being added together to crown a single winner within each division. Some competitors will travel thousands of miles a year to compete to try and claim the world title in 3D archery.
This competitive style has been growing in many other countries and should continue with strong support for many years to come. The major 3d archery groups are the IBO and the ASA are based in Eastern United States, they each have scoring methods. They host a number of competitive shoots across the Eastern United States. There are several classes in each organization that range from hunter all the way up to professional classes; each class shoots at maximum yardages. Similar to target archery, except that the archer attempts to drop arrows at long range into a group of concentric
In plane geometry, an angle is the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle. Angles formed by two rays lie in a plane. Angles are formed by the intersection of two planes in Euclidean and other spaces; these are called dihedral angles. Angles formed by the intersection of two curves in a plane are defined as the angle determined by the tangent rays at the point of intersection. Similar statements hold in space, for example, the spherical angle formed by two great circles on a sphere is the dihedral angle between the planes determined by the great circles. Angle is used to designate the measure of an angle or of a rotation; this measure is the ratio of the length of a circular arc to its radius. In the case of a geometric angle, the arc is delimited by the sides. In the case of a rotation, the arc is centered at the center of the rotation and delimited by any other point and its image by the rotation; the word angle comes from the Latin word angulus, meaning "corner".
Both are connected with the Proto-Indo-European root *ank-, meaning "to bend" or "bow". Euclid defines a plane angle as the inclination to each other, in a plane, of two lines which meet each other, do not lie straight with respect to each other. According to Proclus an angle must be a relationship; the first concept was used by Eudemus. In mathematical expressions, it is common to use Greek letters to serve as variables standing for the size of some angle. Lower case Roman letters are used, as are upper case Roman letters in the context of polygons. See the figures in this article for examples. In geometric figures, angles may be identified by the labels attached to the three points that define them. For example, the angle at vertex A enclosed by the rays AB and AC is denoted ∠BAC or B A C ^. Sometimes, where there is no risk of confusion, the angle may be referred to by its vertex. An angle denoted, say, ∠BAC might refer to any of four angles: the clockwise angle from B to C, the anticlockwise angle from B to C, the clockwise angle from C to B, or the anticlockwise angle from C to B, where the direction in which the angle is measured determines its sign.
However, in many geometrical situations it is obvious from context that the positive angle less than or equal to 180 degrees is meant, no ambiguity arises. Otherwise, a convention may be adopted so that ∠BAC always refers to the anticlockwise angle from B to C, ∠CAB to the anticlockwise angle from C to B. An angle equal to 0° or not turned is called a zero angle. Angles smaller than a right angle are called acute angles. An angle equal to 1/4 turn is called a right angle. Two lines that form a right angle are said to be orthogonal, or perpendicular. Angles larger than a right angle and smaller than a straight angle are called obtuse angles. An angle equal to 1/2 turn is called a straight angle. Angles larger than a straight angle but less than 1 turn are called reflex angles. An angle equal to 1 turn is called complete angle, round angle or a perigon. Angles that are not right angles or a multiple of a right angle are called oblique angles; the names and measured units are shown in a table below: Angles that have the same measure are said to be equal or congruent.
An angle is not dependent upon the lengths of the sides of the angle. Two angles which share terminal sides, but differ in size by an integer multiple of a turn, are called coterminal angles. A reference angle is the acute version of any angle determined by subtracting or adding straight angle, to the results as necessary, until the magnitude of result is an acute angle, a value between 0 and 1/4 turn, 90°, or π/2 radians. For example, an angle of 30 degrees has a reference angle of 30 degrees, an angle of 150 degrees has a reference angle of 30 degrees. An angle of 750 degrees has a reference angle of 30 degrees; when two straight lines intersect at a point, four angles are formed. Pairwise these angles are named according to their location relative to each other. A pair of angles opposite each other, formed by two intersecting straight lines that form an "X"-like shape, are called vertical angles or opposite angles or vertically opposite angles, they are abbreviated as vert. opp. ∠s. The equality of vertically opposite angles is called the vertical angle theorem.
Eudemus of Rhodes attributed the proof to Thales of Miletus. The proposition showed that since both of a pair of vertical angles are supplementary to both of the adjacent angles, the vertical angles are equal in measure. According to a historical Note, w
Skijoring is a winter sport in which a person on skis is pulled by a horse, a dog or a motor vehicle. It is derived from the Norwegian word skikjøring meaning ski driving. Skijoring with a dog is a sport in which a dog assist a cross-country skier. One to three dogs are used; the cross-country skier provides power with skis and poles, the dog adds additional power by running and pulling. The skier wears a skijoring harness, the dog wears a sled dog harness, the two are connected by a length of rope. There are no other signaling devices to control the dog. Many breeds of dog participate in skijoring; the only prerequisite is a desire to run down a trail and pull, innate in many dogs. Small dogs are seen skijoring, because they do not assist the skier. Athletic dogs such as Pointers and herding breeds take to skijoring with glee, as do the northern breeds, such as Siberian and Alaskan huskies, malamutes and Inuit dogs. Golden retrievers, giant schnauzers, Labrador retrievers, many cross-breeds are seen in harness.
Pulling breeds work well such as American bull terriers, Staffordshire terriers, American bulldogs, mastiffs. The sport is practiced recreationally and competitively, both for long distance travel and for short distances. Since many leashed dogs tend to pull a skier with no training, the sport cannot claim a single country of origin; as a competitive sport, however, it is believed that the first races were held in Scandinavia as an offshoot of the older sport of Pulka. Competitive racing has been taken up in North America while its older cousin Pulka racing has not yet become popular. Skijor races are held in many countries. Most races are between 20 kilometers in length; the longest race is the Kalevala held in Kalevala, Russia, with a distance of 440 kilometres. Next is the River Runner 120 held in Whitehorse, with a distance of 120 miles. In the United States and Canada, skijoring races are held in conjunction with sled dog races. In Scandinavia, skijor racing is associated with the older Scandinavian sport of Pulka.
Skijoring races are not limited to purebred Northern breed dogs such as the Siberian husky. On the contrary, the top-ranked racing teams in the world are German shorthaired pointers, pointer/greyhound mixes, Alaskan huskies, or crosses between these breeds. Although some races are unsanctioned, held under the sole guidance of a local club, many races fall under one of three international organizations. In the United States and Canada, ISDRA sanctions many races. In Europe ESDRA provides sanctioning, the IFSS sanctions World Cup races all over the world, as well as a world championship race every two years. At the IFSS World championship event, skijoring races are separated into men's and women's, one-dog and two-dog categories; the USA held the world's largest Skijoring event in February 2011 at the City of Lakes Loppet in Minneapolis. 200 Skijoring teams raced in this event which included the first-ever National Skijoring Championship. The skijoring belt worn by the skier is a wide waistband, clipped around the skier's waist, which may include leg loops to keep it in position.
Rock climbing harnesses are commonly used as skijoring belts. The sled dog harness can be any of the several types of dog harness used for dogsled racing; the skijoring line is at least 2.5 metres long. A longer line is used for a three-dog team. A section of bungee cord is incorporated into the line to absorb the impact of the dog's forward motion or a quick stop by the skier. Special quick-release hitches or hooks are available, used so that the skijorer may unhook the dog's lead rapidly; the skier uses either a classic diagonal stride cross-country technique, or the faster skate skiing technique. In races, the skate-skiing technique is exclusively used; the skis are hot. Classic skis with grip wax are not used for races but are used for extended back-country travel. Skijoring dogs are taught the classic dog sledding commands to start running, turn, to stop and to pass distractions. Training is best done on foot, before the person straps on their skis, to avoid being pulled into objects, like trees or half-frozen creeks.
To participate in races, skijoring dogs must be taught to pass, or be passed by, other teams without interfering with them. An overly friendly attempt by one dog to stop and greet another team passing at high speed can be as problematic as a dog that attempts to nip other dogs in passing. A top skijor racing team can pass other teams head-on, without turning to look at them. Equestrian skijoring consists of a team of a single horse guided by a rider, pulling a person on skis who carries no poles and hangs onto a tow rope in a manner akin to water skiing. In Saint Moritz, competitions involve a riderless horse, guided by the skier. In all cases, the horses have to be trained to accept the presence of ropes and skier behind them and to remain calm in racing conditions. Skijoring behind a horse is said to have originated as a method of winter
Ski orienteering is a cross-country skiing endurance winter racing sport and one of the four orienteering disciplines recognized by the IOF. A successful ski orienteer combines high physical endurance and excellent technical skiing skills with the ability to navigate and make the best route choices while skiing at a high speed. Standard orienteering maps are used, but with special green overprinting of trails and tracks to indicate their navigability in snow. Navigation tactics is similar to mountain bike orienteering. Standard skate-skiing equipment is used, along with a map holder attached to the chest. Compared to cross-country skiing, upper body strength is more important because of double poling needed along narrow snow trails. Ski orienteering events are designed to test both physical strength and navigation skills of the athletes. Ski orienteers use the map to navigate a dense ski track network in order to visit a number of control points in the shortest possible time; the track network is printed on the map, there is no marked route in the terrain.
The control points must be visited in the right order. The map gives all information the athlete needs in order to decide which route is the fastest, including the quality and width of the tracks; the athlete has to take hundreds of route choice decisions at high speed during every race: a slight lack of concentration for just a hundredth of a second may cost the medal. Ski orienteering is objective; the clock is the judge: fastest time wins. The electronic card verifies. International competitions The World Ski Orienteering Championships is the official event to award the titles of World Champions in Ski Orienteering; the World Championships is organized every odd year. The programme includes Sprint and Long Distance competitions, a Relay for both men and women; the World Cup is the official series of events to find the world's best ski orienteers over a season. The World Cup is organized every year. Junior World Ski Orienteering Championships and World Masters Ski Orienteering Championships are organized annually.
World-wide sport Ski orienteering is practiced on four continents. The events take place in the natural environment, over a variety of outdoor terrains, from city parks to countryside fields and mountain sides - wherever there is snow; the leading ski orienteering regions are Asia and North America. National teams from 35 countries are expected to participate in the next World Ski Orienteering Championships to be held in Sweden in March 2011. Ski orienteering is on the programme of the Asian Winter Games and the CISM World Military Winter Games; the IOF has applied for inclusion of ski orienteering in the 2018 Olympic Winter Games and will apply to FISU for inclusion in the 2013 Winter Universiades. A person taking part in competitions in ski orienteering is equipped with: Clothing adequate for cross-country skiing and skis and ski poles. An orienteering map provided by the organizer, showing the control points which must be visited in order; the map is designed to give all the information the competitor needs to decide which route is the fastest, such as the quality of the tracks and distance.
Green lines on the map show a trail suited to race on skis. Depending on the thickness and continuity of the lines, the competitor makes decisions about which route is the fastest between control points. Map holder: a map holder attached to the chest makes it possible to view the map while skiing at full speed. Optionally lighter type of compass is attached to the skier's arm. An electronic punching chip; the International Orienteering Federation had applied for ski orienteering to be included in the programme of the 2018 Olympic Winter Games. However this was unsuccessful. In the past few years, ski orienteering has grown in terms of global spread; the growth has been boosted by the inclusion of ski orienteering into the Asian Winter Games and the CISM World Military Winter Games. Media related to Ski orienteering at Wikimedia Commons International Orienteering Federation Ski orienteering presentation Ski orienteering presentation on YouTube